The accord, signed by Sudan's President Omar al-Bashir and Chad's President Idriss Deby, calls on the two African nations to work together to halt rebels and opposition groups from staging cross-border attacks and support the African Union's efforts to restore stability in Darfur.

The deal comes amid fears that the bloodshed in Sudan's western Darfur region is increasingly spilling over the border into neighboring Chad. Janjaweed militiamen who have terrorized Darfur regularly launch raids into Chad, attacking civilians. Meanwhile, Sudanese-backed Chadian rebels stage attacks into Chad, prompting Chadian army assaults into Darfur.

The four-year conflict between ethnic African rebels and pro-government janjaweed militia in the western Sudanese region has killed more than 200,000 people and displace 2.5 million Darfurians.

Khartoum denies supporting the janjaweed, but the International Criminal Court in The Hague has accused a junior Sudanese Cabinet minister of being the militia's paymaster and a member of the Sudanese security forces of being a janjaweed commander.

The current 7,000 AU peacekeeping force in Darfur has struggled to contain the fighting in the region, which is the size of France. Khartoum has recently agreed to allow a batch of 3,000 U.N. peacekeepers reinforce the AU troops in Darfur.